This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 9900577-9 filed in Sweden on Feb. 19, 1999; the entire content of which is hereby incorporated by reference.
The present invention relates to a method of passively aligning at least one substrate-carried optical fibre with at least one optical device, and to a device which includes at least one optical fibre disposed on a substrate and aligned with at least one optical device.
Optocoponents are expensive to produce. A considerable part of this expense is entailed by the fact that optocomponents are equipped with an optical connection that has high tolerance requirements. It is necessary to position the fibre with great precision; with respect to an optical chip a precision of about 1/1000 mm.
This is normally effected by so-called active alignment, wherein an electric current is applied to an optical chip so as to cause said chip to generate light which, in turn, is launched into an optical fibre. The launching maximum can be determined, by moving the fibre in extremely small increments whilst measuring the light launched into the fibre at the same time. The fibre is then fixed in this maximum position. The method is complicated, laborious and extremely demanding with respect to the fine-mechanical component parts.
In an endeavour to reduce costs, an alternative alignment method, so-called passive alignment, is being used to a progressively increasing extent. One distinguishing feature of this method is that the optochip is not energised during the alignment process, but is, instead, fastened together with the optofibre on a common carrier in predetermined and well-defined positions. The carrier is normally comprised of silicon and provided with micromechanical structures for facilitating positioning of the optochip and optofibre.
Patent Application JP 09281360 teaches a structure that includes a plurality of optical fibres disposed in V-grooves. where the fibres are aligned relative to a light-emitting source.
One problem associated with this solution is that the crystal orientation of the silicon disc must be accurately determined, in order to achieve the desired groove geometry.
The object of the present invention is to at least reduce the aforesaid problems.
One advantage afforded by the present invention is that the silicon disc can be patterned regardless of crystal orientation.
Another advantage afforded by the invention is that the U-grooves can be made late in the process, owing to the fact that no aggressive wet chemicals are used. This enhances the degree of freedom in the process sequence, the compatibility between process steps, and also increases the yield. Yet another advantage afforded by the invention is that the U-grooves can be etched to a high degree of precision with respect to groove width and length, and that the walls of the U-grooves are vertical in relation to a substrate surface.
Yet another advantage afforded by the invention is that the grooves can be produced with essentially vertical walls and a groove bottom surface which is essentially parallel with said substrate surface, regardless of the geometry of the groove in a plane parallel with said substrate surface.